Prior to EPA particulate emissions regulations for wood heaters, established the late 1980's, numerous models of conventional wood stoves enjoyed the sales benefit of the convenience feature of being capable of fueling by way of a top loading door.
Consequently, in order to comply with EPA regulations, many manufacturers opted for utilizing a non-catalytic secondary combustion design. This typically employed what is commonly known as a “Scandinavian” baffle in combination with a secondary air source directly below the baffle to achieve low particulate emissions performance, or “clean burn.” These non-catalytic woodstoves employ a fixed position horizontal or near horizontal Scandinavian baffle and a series of tubes or a manifold to supply diffused secondary air directly beneath the baffle to provide for the “clean burn” characteristic. Scandinavian baffle designs, however, do not allow for fuel to be loaded through a top door to the firebox as the baffle effectively blocks vertical delivery to the firebox by impeding a majority of access to the firebox fuel holding area.
Woodstoves incorporating Scandinavian, or horizontal baffles, have an extended flame path which promotes cooler stack temperatures with the benefit of minimized flue gas temperature entering the chimney. The cooler stack temperature allows closer installation clearances to combustibles (adjacent walls and structure) in comparison to other typical top loading non-catalytic technology currently available and of comparable energy output.
In the past several years there have been introductions of non-catalytic designs featuring a top loading door. The majority of currently available, non-catalytic wood heaters with top loading door capability incorporate a secondary combustion or “down drafting” firebox system and a bypass damper at the flue entrance. Down drafting does not employ a baffle but instead the bypass damper or bypass gate directs the products of primary combustion downward through the coal bed into an entrance to a secondary combustion chamber located behind the firebox. The hot gases are exposed to a secondary air source in the secondary combustion chamber to achieve low emissions performance. Consequently, the lack of a secondary baffle in these systems allows for a top loading feature. In order to refuel the non-catalytic wood heaters with top loading door, the bypass gate must be opened allowing a straight path to the chimney, otherwise large amounts of combustion products would enter the room should the fuel load door be opened.
An example, of a wood burning stove having a top loading door and down-draft combustion is the LEYDEN top loading cast iron wood stove available from Lopi Fireplace and manufactured by Travis Industries.
U.S. Pat. Nos. 6,688,302 and 7,216,645 issued to Henry et al. disclose a wood burning stove having a manually operated top loading door and a manually operated movable baffle. The baffle is movable to a position behind the opening when the top loading door is opened for loading the wood burning stove and for directing combustion gas behind the opening in the stove and out the chimney. The lower portion of the baffle is disposed in the combustion chamber when the baffle is in the open position. In addition, the lower portion of the baffle is also maintained in the combustion chamber when moving the baffle to the closed position to the open position.
There is a need for further methods for operating wood fired appliances, and more specifically, to methods for operating wood fired appliances having a cooperating top loading door and movable baffle.